1. Field of the Disclosure
The present disclosure relates generally to controlling toner development in an image forming device and more particularly to methods of automatically controlling toner development by reducing toner density during a life of an imaging unit in an image forming device to reduce any risk of carrier bead development.
2. Description of the Related Art
An imaging unit in electrophotographic devices (i.e., mono or color laser printers) includes a photoconductor portion and a toner development portion. When an electrophotographic device performs a print operation, a photoconductor is initially charged to a uniform potential. Appropriate areas of the photoconductor are then discharged by a laser or light emitting diode system to create a latent electrostatic image thereon. This discharged portion of the photoconductor is presented to the toner development portion and toner is developed to either the discharged portion or charged portion of the photoconductor. The photoconductor is then rotated to where the toner developed to the photoconductor is transferred to an image medium which may be a sheet of media or an intermediate transfer member (for subsequent transfer to a media sheet).
In a dual component toner development system, toner particles are mixed with particulate additives which include magnetic carrier beads. Magnetic carrier beads help in transporting the toner particles to the discharged portion of the photoconductor. However, over the life of the imaging unit, changes to the toner, carrier beads, and the photoconductor all have an impact on toner development.
In particular, it will be understood that as photoconductors age in typical dual component development systems, a polymeric layer of each photoconductor wears away, thus increasing a surface charge thereof. This increase in surface charge of the photoconductor translates to an increase in a likelihood of the magnetic carrier beads also developing with the toner particles onto the discharged portions of the photoconductor. In addition to the wearing of the polymeric layer of the photoconductor, a polymeric coating of the carrier heads wears out overtime, resulting in a change in conductivity thereof andior the ability to charge the toner. Other extra particulate additives from the toner particles can also accumulate on the carrier bead surface, impacting the ability for the toner to reach a charging site on the carrier beads. These aforementioned changes over time affect the amount of toner being developed onto the photoconductor surface. When the imaging unit reaches a rated point in its life in which the carrier beads have accumulated wear or have become covered with the above-mentioned extra particulate additives, or the polymeric layer of the photoconductor has become worn, the amount of carrier heads unintentionally developed to the photoconductor surface may increase as the developed toner mass increases.
Carrier bead development on the photoconductor occurring with toner development is undesirable and is thought to eventually cause damage to the imaging unit. Typically, a life of the imaging unit is rated at a point where a level of carrier bead development will not be detrimental to the system. Continuing to use the imaging unit beyond this point will increase the risk of carrier beads damaging the various components of the image forming device, such as the intermediate transfer belt and fuser.